1. Technical Field
The present invention relates to a vehicle steering link assembly. In particular, the present invention relates to a vehicle steering link assembly which extends between two steerable wheels of a vehicle and which is adjustable in length.
2. Description of the Prior Art
Vehicle steering linkage connects the steering gear of a vehicle with the steerable wheels of the vehicle. The steering linkage includes one or more links which transmit steering force from the steering gear to the steerable wheels, to turn the steerable wheels in response to a driver input to the steering gear.
Medium to large trucks, such as Class 4 to Class 8 trucks, commonly employ a cross steer linkage. In a cross steer linkage, a drag link transmits steering force from the steering gear to the steerable wheel nearest the steering gear. A tie rod assembly including an intermediate tube extends across the vehicle from that steerable wheel to the steerable wheel on the opposite side of the vehicle. The intermediate tube transmits steering force to the steerable wheel on the opposite side of the vehicle.
In this known steering linkage, the ends of the intermediate tube commonly are internally threaded and receive externally threaded portions of parts attached to the steerable wheels. The threads on the opposite ends of the intermediate tube are of opposite hand. Thus, the overall length of the tie rod assembly is adjustable by rotation of the intermediate tube about its axis. This adjustment is used to set the toe of the steerable wheels of the vehicle.
It is common to employ a clamp placed around each threaded connection to prevent relative rotation between the intermediate tube and the threadedly connected parts once the vehicle toe is set. These clamps must be located axially a specific distance from the end of the intermediate tube in order to clamp properly. The clamps must also be free to rotate about the intermediate tube when loosened, so that the clamps may be set in a desired rotational position regardless of the rotational position of the intermediate tube, to avoid contact with other parts of the vehicle.
In a known method of making an intermediate tube for a medium to large truck such as a Class 4 to Class 8 truck, the end portions of a parent tube are reduced in diameter by swaging to a size selected to receive a vehicle part of a particular outer diameter. On each end portion, short beads of weld material are placed on the outer circumferential surface of the intermediate tube, on either side of the clamp location, to locate the clamp axially on the tube while still allowing the clamp to rotate. The beads of weld material extend circumferentially only for a small distance around the intermediate tube. This welding process adds a separate operation to the other operations needed in forming the tube, and is relatively expensive and time consuming. Thus, it is desirable to be able to locate the clamp axially on the intermediate tube in another manner.
U.S. Pat. No. 3,801,207 shows one manner of locating a clamp axially on a tubular member in a vehicle steering linkage. Several protuberances are stamped in a piece of sheet steel which is then curled into a tubular shape to form a turnbuckle. A clamp placed around a threaded connection between the turnbuckle and a tie rod end is tightened to prevent relative rotation between the threadedly interconnected parts. The protuberances stamped in the sheet steel are received in a channel in the clamp. The protuberances and the channel cooperate to block axial movement of the clamp relative to the turnbuckle. The clamp is rotatable on the turnbuckle.
On an intermediate tube for a medium to large truck, such as a Class 4 to Class 8 truck, it is not feasible to locate a clamp axially in the manner shown in U.S. Pat. No. 3,801,207. This is because an intermediate tube for such a vehicle is typically five feet or more in length, 11/4" or more in diameter, and has a wall thickness of up to 3/8". It is not feasible to stamp protuberances in such material, to cold form such a part, or to make a die set over five feet long to stamp and curl such a part.